1. Field of the Invention
This disclosure relates to an air inlet system for furnishing charge air, including recirculated exhaust gas, to the cylinders of a reciprocating internal combustion engine.
2. Related Art
Diesel engines, while offering excellent fuel economy, must be controlled ever more stringently in terms of exhaust emissions, particularly oxides of nitrogen (NOx) and particulate matter. In an effort to control NOx without causing an undue loss in fuel economy, engine designers have relied upon increasingly higher amounts of exhaust gas recirculation (EGR). More specifically, EGR rates of approximately 30% at peak power conditions and 60% at low speed and load are on the horizon. Unfortunately, it is difficult to furnish very high amounts of EGR to an engine's cylinders in a uniform manner. That is, without providing too much EGR to one cylinder while too little to others. Maldistribution of EGR causes an engine to run rough and with unacceptable emissions. Furthermore, this can lead to undesirable temperature nonuniformities in various engine components. Although an extremely lengthy intake tract may be used to provide adequate mixing of EGR with the other components of charge air, a long intake tract may not be package feasible, particularly in vehicular applications.
It would be desirable to provide an inlet system for an internal combustion engine, such as a diesel engine, having the capability of fully mixing large amounts of EGR in a charge air stream so as to prepare a uniform mixture for induction into the engine's power cylinders. It would further be desirable to minimize the package volume required for an engine's air induction system.